1. Field of the Invention
The invention relates to a memory module, particularly the memory module provides IC memory chips are installed in detachable manner.
2. Description of the Prior Art
The conventional memory module 10 normally has a structure shown in FIG. 1 which is formed by fixedly installing IC memory chips 70 on one side or both sides of a printed circuit board (PCB) 11 by soldering.
Take the memory module 10 shown in FIG. 1 as an illustrated example, the PCB 11 has a plurality of printed circuit sets 12 on the surface, and each printed circuit set 12 has multiple conductive contacts 13 through which IC memory chip 70 can be installed on the PCB 11 by soldering to form an electric connection with the corresponding printed circuit set 12. Therefore, by employing the same manner a plurality of IC memory chips 70 can be arranged and installed on the PCB 11 to form a memory module 10.
In the memory module 10, the IC memory chip 70 is the major element, and the packing method of the IC memory chip 70 has been gradually improved to involve from the Thin Small Outline Package (TSOP) method to the Ball Grid Array (BGA) method.
Besides, the IC memory chip 70 with Ball Grid Array package shown in FIG. 1 can be installed on PCB by employing Surface Mount Technology (SMT) to join the pads on the underside of the IC memory chip 70 and the conductive contacts 13 of each printed circuit set 12 on the PCB 11 by soldering to fix the IC memory chip 70 on the PCB 11.
However, the drawback of fixing the IC memory chip on PCB 11 by means of pads and soldering is that it will cause inconvenience in replacement and maintenance of IC memory chip. When the IC memory chip 70 is to be removed for repair, in addition to the removal of the original pads by de-soldering with high temperature, new pads must be re-embedded to IC and the repaired IC must be re-positioned and re-soldered to the PCB again. However, there are some difficulties on re-embedding the pads and re-positioning the repaired IC.
Especially, during removal of pads by high temperature the undamaged IC memory chips 70 are likely to be damaged due to high temperature, and, the removed pads and the soldering past as well as flux used during re-embedding the new pads will cause environmental pollution problem that is detrimental to the environment.